Service

SERVICE

JOE MINTON

Oil-thirsty Z-1

I have a 1982 Kawasaki LTD1000 with 20,000 miles on it. It’s burning about a quart of oil every 600-700 miles. A mechanic says that he can fix the problem by putting in new rings and the other, “usual" things that go along with this. He is going to charge me about $600, and says that the engine will run better than new, but I’m worried about being ripped off. What should I expect to get for my $600?

Ron Sklar

Albuquerque, New Mexico

Kawasaki Z-l engines seldom burn oil at 20,000 unless they have gotten very hot sometime in their lives. An excessively high operating temperature is the most common reason air-cooled motorcycle engines might need an early overhaul. High temperatures can do more than weaken piston rings.

They can also damage valve-guide oil seals, cook gaskets, cause excessive valve wear, collapse piston skirts and warp cylinders. Your engine, once it is torn down, should be carefully inspected for these possible problems.

There is a reasonable chance that the engine will need its cylinders bored to make them round and straight, and to establish the correct clearance between the cylinders and pistons. Certainly, the valve seats will need to be > touched-up and the valves lapped. If the valve guides are worn, they will need replacing. However since your engine has only 20,000 miles on it, I suspect that cylinder boring and a valve job will fix it up again. The price your mechanic quoted seems appropriate, if he can indeed deliver on his promise of high-quality work.

The secret to a “better than new" engine is caref ul assembly. The cylinders must be truly round and straight. They should have a very fine, almost-mirror-like finish. The pistons should be fitted to the minimum clearance specified in the shop manual. It won 7 hurt to smooth the ports a bit, especially around the valve-seat areas. The cams of a Z-I motor should be timed to 104-106 degree lobe centers for best all-round street performance.

If the cams are set at 108-110, the engine might make a bit more power at high rpm and might turn a little better time at the strip, but midrange power will suffer.

Your engine's oil temperature shouldn 7 be allowed to go above 240 degrees Fahrenheit, and you might want to install a temp gauge to establish just how hot it is getting. I would also install an oil cooler. A Lockhart 700 cooler will drop the temperature of your engine oil up to 35 degrees (according to some testing I did years ago) and is the most effective oil cooler I know of

Plug problems

I notice in my 1984 Honda V65 Sabre owner’s manual that the recommended replacement interval of the spark plugs is every 4000 miles. I know that most automobile plugs last 25.000 miles or more, so why not for motorcycles?

John Kawalec

Sterling, Virginia

A liquid-cooled motorcycle engine burning lead-free gasoline, like yours, should get very long life from its spark plugs. They should last more than 4000 miles. However, there are two reasons why motorcycle plugs do not generally last as long as an automobile's.

Motorcycle engines often develop more pressure and higher temperatures in their combustion chambers than an automobile. The extra stress, heat and scrubbing action in the> chambers result in a higher wear rate for the plugs. The main reason, though, for a motorcycle's shorter plug life is ignition energy. Contemporary automobiles have more energetic ignitions than almost any motorcycle. A bike's weaker ignition is more sensitive to rounded electrode gaps and more susceptible to the grounding effects of fouling. When we get truly energetic ignitions, our plugs will last as long as the ones in Aunt Martha's Chevy.

Tippy Triumph

I have a 1976 Triumph Bonneville 750 which develops a severe wobble on those rare occasions when it sees 80 miles per hour or better.

Both wheels have been trued and balanced, and there is no slop in the steering head. Do I need a steering damper?

Bret Samms

Coeur D'Alene, Idaho

Are you sure it's a wobble? A wobble is when the front-fork assembly oscillates violently from side to side. A weave, on the other hand, is when the rest of the chassis oscillates from side to side. There is a difference, and it is important.

Most of us refer to either condition as a wobble. A genuine wobble will have the handlebar shaking very rapidly (six to 10 cycles per second) while the rest of the bike remains relatively steady. A weave will leave the handlebar nearly steady while the rest of the chassis oscillates at two to three cycles per second. There are many possible causes of either condition.

A steering damper will help damp a tendency to wobble. However, the forces the damper puts into the chassis will also tend to initiate a weave.

Before you install a steering damper, be sure that it is a wobble that you are trying to eliminate.

Recheck all bearings that hold the chassis together: steering head, wheels and swingarm pivot. Make doubly sure the spokes are tight and that the rims and tires run true. Tires are an important part of any motorcycle's stability. If the tires you are running are significantly different in shape or stiffness than what Triumph developed the Bonneville with, you could have a stability problem. Check everything: Triumphs shouldn 7 wobble. EE